SQL包含的HQL等价物

Question

我正在尝试编写一个HQL查询来选择包含子集合中对象的对象.

例:

比赛对象

ContestID  
ContestName  
RequiredCountries -> one to many collection of Country objects  

国家对象

CountryCode  
CountryName  

sql相当于我想要的:

SELECT * FROM CONTEST C  
WHERE C.CONTESTID IN(SELECT CONTESTID FROM CONTEST_COUNTRY CC INNER JOIN COUNTRY CTRY ON   
CC.COUNTRYCODE = CTRY.COUNTRYCODE WHERE COUNTRYCODE='USA')

要么

SELECT * FROM CONTEST C  
WHERE EXISTS(SELECT CONTESTID FROM CONTEST_COUNTRY CC INNER JOIN COUNTRY CTRY ON 
CC.COUNTRYCODE = CTRY.COUNTRYCODE WHERE COUNTRYCODE='USA' AND CC.CONTESTID=C.CONTESTID)  

我有这个hql,它有效,但似乎不是一个好的解决方案 -

from Contest C  
where (from Country where CountryCode = :CountryCode) =  some elements(C.RequiredCountries) 

我也考虑加入Country,但由于我没有表示关系的对象类,所以我不确定如何加入HQL.

任何人有任何想法或建议吗？这应该很容易.

Answer 1

试试这个:

from Contest Ct, Country Cr
where Cr.CountryCode = :CountryCode 
    and Cr.Country in elements(Ct.RequiredCountries) 

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Answer 2

前一个将工作(至少它适用于我 - 我正在使用休眠),但'正确的方式'是'成员'运算符...像这样:

select ...
from Contest Ct, Country Cr
where Cr.CountryCode = :CountryCode
  and Cr.Country member of Ct.RequiredCountries

(见http://docs.oracle.com/javaee/6/tutorial/doc/bnbuf.html#bnbvk)

我认为elements()是HQL扩展.我认为尽可能使用标准(JPQL)会更好.